It is worth noting that "sleep time" usually refers to when the display turns off or the system enters a low-power state. This is distinct from "hibernate" (which saves your session to the hard drive and powers off completely) or a screen saver (which is purely visual). By customizing these sleep settings, you can prevent your computer from interrupting long downloads or presentations while still saving electricity when you step away.
Before we dive into the process, let's discuss why you might want to change the sleep time on your computer. Here are a few scenarios: how do i change the sleep time on my computer